Hong Kong's anti-mask law will not curtail the freedom of expression and peaceful assembly, Matthew Cheung, chief secretary for administration of China's Hong Kong Special Administrative Region (HKSAR) government, said Sunday.

The HKSAR government on Friday invoked an emergency law to put in place an anti-mask regulation as a deterrent to rioters, most of whom have used masks to conceal their identities in the months-long unrest.

In his blog, Cheung said the move is intended to deter violent acts committed by masked rioters and to assist with the police in their investigation, the official said.

The HKSAR government has said Hong Kong is in serious situation as rioters continued to set fire, vandalize shops and public facilities and assault police officers and residents with different political views.

"We can not sit idly by and allow violence to escalate and the situation to worsen without recourse to the existing legislation," he said, stressing that the HKSAR government is resolute in combating violence and police will enforce the law in a rigorous and decisive manner.

Cheung also said the law will be tabled for review after the HKSAR Legislative Council (LegCo) resumed meeting on Oct. 16, refuting the accusations that the government bypassed the LegCo.